The present invention relates to a process for producing a semiconductor device that has a wiring structure made from a silicide film.
A known process of this type is illustrated in FIGS. 4a and 4b. As shown in FIG. 4a, a film 15 of a silicide (an alloy of silicon and a metal) is deposited and is brought into contact with an impurity diffusion layer 12 provided in a surface layer of a semiconductor substrate 11 of silicon (Si), for example, through contact holes 14 in an insulating layer 13. Thereafter, as shown in FIG. 4b, a second insulating layer 16 and wiring 17 are formed to produce a semiconductor device. Since a heat treatment is carried out at 800.degree. C. or higher, in general, even after the formation of the silicide film 15, impurities in the vicinity of the surface of impurity diffusion layer 12 are absorbed into the silicide. As a result, the impurity concentration in the semiconductor substrate 11 at the interface between the impurity diffusion layer 12 inside substrate 11 and the silicide film 15 is reduced and hence the contact resistance between silicide film 15 and impurity diffusion layer 12 increases.
As a result of the heat treatment that is carried out after the formation of silicide film 15, impurities in the vicinity of the surface of the impurity diffusion layer 12 in the semiconductor substrate 11 are absorbed into the silicide, causing a lowering of the impurity concentration in semiconductor substrate 11 at the interface between impurity diffusion layer 12 and silicide film 15, which results in an increase in the contact resistance between silicide film 15 and impurity diffusion layer 12.